Mount Prospect, Illinois 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

060
FXUS63 KLOT 132024
AFDLOT

Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
324 PM CDT Sat Jun 13 2026

.KEY MESSAGES...

- Scattered thunderstorms this evening, a few may be strong to
  severe.

- Dangerous swimming conditions at NW Indiana Lake Michigan
  beaches Sunday.

- Cooler temperatures early next week.

- Shower and thunderstorm chances return Tuesday and Wednesday.
  The possibility exists for another severe weather event on
  Wednesday.


&&

.DISCUSSION...
Issued at 324 PM CDT Sat Jun 13 2026

Recently, a few isolated showers and storms developed across
parts of LaSalle eastward into southern Kendall and Grundy
counties, but have since decayed. Otherwise, we continue to
monitor the threat for more substantial scattered showers and
storms (some of which could be strong/severe) with a cold
frontal passage this evening. Forecast guidance continues to
support an uptick in scattered shower and thunderstorm
development late this afternoon and evening in advance of this
front. This appears plausible given that a mid-level impulse
currently shifting eastward across IA will be overspreading the
frontal zone as it moves into northern IL after 5 pm this
evening. Additionally, low-level moisture return continues in
advance of the front, and is noted by surface dewpoints already
increasing into the upper 60s to near 70 in parts of northern
IL.

Considering the environment in which these storms are, and will
be, developing features deep-layer bulk shear in excess 35 kt,
there remains a threat for some storms to become strong to
severe into this evening. Accordingly, the SPC continues to have
our area in a level 1 of 5 severe threat through this evening.
While certainly not looking to be an outbreak of severe storms
like the area experienced on Thursday, a few of the strongest
storms could produce localized damaging wind gusts in excess of
60 mph and possibly a few instances of hail. The main threat of
storms will end from northwest to southeast through the mid to
late evening hours.

A few lingering scattered showers may linger in the wake of the
cold frontal boundary for a period late tonight into early
Sunday morning as the main mid-level impulse dives into the
area. However, this activity is expected to quickly exit the
region early Sunday, setting up a precipitation free day for the
area. Temperatures will be much cooler for Sunday in the wake
of this cold frontal passage, as breezy northwest winds (gusting
up to 30 mph) usher in a cooler airmass. Accordingly, expect
high temperatures generally in the low to mid 70s Sunday
afternoon. The only real weather concern for Sunday is at Lake
Michigan Beaches across northwestern Indiana, where the onshore
breezy winds build waves up to 3 to 5 feet, setting the stage
for a high swim risk. With this in mind, we have opted to hoist
a Beach Hazard statement for our Lake IN and Porter county
beaches on Sunday.

Another tranquil weather day is anticipated on Monday, though
with a bit warmer temperatures. Thereafter, upper troughing,
anchored by a Hudson bay area low, will support an enhanced belt
of mid and upper-level northwesterly upper-level flow across
the central CONUS through mid to late week. This should result
in a return to a more active weather pattern again (return of
showers and thunderstorms) for the middle of next week, which
may drive another significant impulse into the lower Great Lakes
region on Wednesday. Wednesday is thus another day to watch
closely for our next potential notable severe weather threat.

KJB

&&

.AVIATION /18Z TAFS THROUGH 00Z MONDAY/...
Issued at 1253 PM CDT Sat Jun 13 2026

Key Messages:

- Period of showers and thunderstorms this evening (00Z-04Z
  window).

- Breezy southwest winds this afternoon turn north-northwesterly
  tonight in wake of a cold frontal passage.

We continue to monitor the threat and potential timing of
showers and thunderstorms late today into this evening as a cold
front moves into the area. Confidence continues to increase
that a period of at least widely scattered storms will develop
across northern IL into early this evening. Accordingly, we have
opted to convert the PROB30 group for TSRA to a tempo group in
the latest 18Z tafs (all sites with the exception of RFD). The
primary window for the these potential storms is generally
looking to be in the 01-04Z timeframe. KRFD may remain displaced
north of the better coverage of storms this evening, so we
opted to hold on with the going PROB30 for now. A few lingering
light showers may persist for a period overnight (following the
main time window for storm potential highlighted in the tempo
group). A more formal mention for these overnight showers may
be needed in future TAF updates. This lingering activity is
expected to move out of the area into early Sunday morning,
with an otherwise dry Sunday with VFR conditions anticipated
for the area.

Southwest winds will remain gusty (into the mid 20 kt range) in
advance of the approaching cold front this afternoon. As the
front passes, expect a shift to a northwest direction mid to
late this evening, then north-northwesterly overnight. Gusty
northwesterly winds (gusts of 20-25 kt) are then likely during
the day Sunday.

KJB

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...None.
IN...Beach Hazards Statement from Sunday morning through Sunday
     evening for INZ001-INZ002.

LM...None.

&&

$$

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